In conventional ophthalmic medical care for corneal transplantation, special observation apparatuses such as microscopes capable of observing the thickness of a cornea for transplantation, the size, the conditions and the like of corneal cells, and photographing or measurement of the same have been prevailing for achieving safe and optimal transplantation of the cornea. As an observation apparatus of a cornea for transplantation, for example, a microscope has been known in which the cornea for transplantation contained in a container such as a sample vial or a dedicated vessel for a cornea for transplantation is mounted together with the container etc., on an optical axis of a microscope to carry out observation. As such a microscope, a specular microscope has been ordinarily used.
Observation or the like of such a general cornea for transplantation is carried out with a specular microscope by observing the cornea for transplantation contained in a container from the bottom face side of the container. Thus, since a specular microscope is used for observing a cornea for transplantation, it is difficult to specify the direction in which the cornea for transplantation should be moved for obtaining a magnified view when any magnified view is not captured. In addition, even in the case in which a magnified view is captured, it is difficult to ascertain which part of the cornea for transplantation is shown by this magnified view.
Such difficulties result from the state of the cornea for transplantation contained in the sample vial filled with a chemical liquid without being fixed, as it is not necessarily positioned at the center of the vessel. In addition, due to the construction of the specular microscope, it is necessary to move the cornea for transplantation as a subject to an intersection point of the axis of the irradiated light and the axis of the observed light in transversal and horizontal directions as well as vertical direction for adjustment. Particularly, in the case in which, for example, the vessel cannot be visually observed from above due to a lid of the sample vial or the like not being transparent, or the cornea is likely to move in the vessel, the magnified view captured frequently corresponds to the end of the cornea or out of the cornea. Accordingly, there exist disadvantages of necessity of spending energy for position adjustment in order for the observer to observe the cornea, thereby necessitating waste of labor and time for observation.
Under such circumstances, for the purpose of overcoming the aforementioned disadvantages, an observation apparatus provided with a positioning assistance means such as a mirror or camera that reflects the observed view region, on the back face side of the sample vial has been also proposed in order to ascertain the magnified target region in this observation apparatus (see Japanese Patent No. 3922486). However, it is necessary to ascertain the position by peering down the mirror, or to ascertain the position by changing a low-magnification lens into the optical system according to the positioning assistance means, and thus the workability is not necessarily superior due to, for example, needs for carrying out this operation each time following changing the observation positions. Therefore, even in commercially available apparatuses for observing a cornea for transplantation provided with a positioning assistance means, the positioning assistance means itself has not been fully utilized under current situations.